This invention relates to the use of salicylic acid derivatives. More particularly, it relates to compositions containing salicylic acid derivatives, and the topical use thereof on animals, including man, for providing an anti-inflammatory effect.
Tissue inflammation is the result of interconnected physiological events. Inflammation of the skin which is associated with tissue damage can result from various skin disorders such as eczema, psoriasis, seborrheic dermatitis, contact dermatitis, allergic dermatitis, etc. Inflammation is also associated with tissue damage resulting from ultraviolet or thermal burns, attack by certain micro-organisms, insect bites, stings, etc. Inflammation of deeper structures, the muscles, tendons, bursa, and joints, which is associated with tissue damage, can result from physical trauma, e.g. sprains, strains, contusions, strenuous exercise, etc. Such inflammation may result in bursitis, tendinitis, and muscle soreness. Inflammation is also associated with tissue damage resulting from metabolic disorders, such as gout, or from immunologic disorders, such as rheumatoid arthritis, or from changes associated with aging, such as osteoarthritis.
Symptoms of inflammation are erythema (redness), edema (swelling), heat, pain, and loss of function. The immediate consequence of tissue damage is the release of certain chemical agents which are mediators of inflammation, i.e. these materials evoke and intensify the events which result in the redness, swelling, pain and heat. Examples of these chemical agents are histamine, seratonin and the kinins.
One of the important mediators of inflammation are certain prostaglandins. In contrast to histamine, seratonin and the kinins, the prostaglandins are continuously biosynthesized and released from cells at the inflammatory site. Thus, the prostaglandins have a longer lasting effect. Various anti-inflammatory compounds are known inhibitors of prostaglandin synthesis. One commonly used anti-inflammatory drug is aspirin. Aspirin, of course, is a well known oral drug; however, recent studies have also indicated aspirin can delay and decrease inflammation in animals and in humans when applied topically. However, it has been found that a relatively high concentration of aspirin must be topically applied before it is effective for its intended function. Unfortunately, the repeated use of a high level of aspirin causes primary irritation and peeling of the superficial layers (the stratum corneum) of the skin. Accordingly, there is a need for a compound to be used topically which will alleviate inflammation without adverse secondary effects.
Various esters of acetylsalicylic acid have been suggested for oral or parenteral use to provide an anti-inflammatory effect. (For example, see U.S. Pat. Nos. 749,980; 1,436,304; 2,474,005; 3,518,297 and British Pat. No. 1,379,009.) However, it has been found that oral or parenteral administration of the esters of acetylsalicylic acid does not provide satisfactory anti-inflammatory effects. It is believed the esters decompose prior to arriving at the site of inflammation or are poorly absorbed into the blood.
Accordingly, it is an object of this invention to provide compositions which are useful as anti-inflammatory agents.
It is another object of this invention to provide compositions which can be topically applied to skin to alleviate inflammation.
It is still another object of this invention to provide a composition containing a salicylic acid derivative which can be efficiently and effectively used for topical application.
A still further object of this invention is to provide a method of topically administering to skin a composition capable of alleviating inflammation in various skin disorders associated with disease and trauma and also various disorders of the deeper structures, muscles, tendons, bursa and joints associated with the disease and trauma.
These and other objects will become apparent from the description to follow.
As used herein all percents and ratios are by weight unless otherwise indicated.